My upcoming Oct 2019 trip will be my 21st & 22nd time on the Auto Train (the first was in 2000). We have always booked a room or roomette so I can't help you with coach but most everything else is the same (the dining car for the rooms section is a bit upgraded with a table cloth and the menu might be considered an upgrade). First, we arrive the day before and stay at the (now closed) Comfort Inn one block away - it has reopened as a Holiday Inn. I am always concerned about missing the train due to some traffic jam driving down the day of departure so for me it's worth the extra night. The train loading/check in begins around 11am. It is worth showing up early to register because the meal times are given out at check in - usually 3 seatings 5pm, 7pm and 9pm - this depends on how crowded the train is so there may only be two seatings, but if you want your preferred time you need to get there early. Once you check in, you don't need to board right away, just show back up by 2pm. We use this time to have lunch and pick up supplies at the market across the street.
Have your train bags ready to go with whatever you need for the night, once you turn over the car you have no access until the next day.
Sleeping on the train - well, it is hit or miss. Sometimes the ride is fairly rough, others have been pretty smooth. I usually do ok.
I could probably ramble on for awhile, so just ask me questions. Also, if you decide to get a roomette, the prices vary over time. Once it is booked, check the prices as it gets closer to your trip - if it goes down, just call and they will refund the difference.
